HECTD3 Mediates an HSP90-Dependent Degradation Pathway for Protein Kinase Clients.
HECTD3 Mediates an HSP90-Dependent Degradation Pathway for Protein Kinase Clients.
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DOI：
10.1016/j.celrep.2017.05.078
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发表时间：
2017-06-20
期刊：
影响因子：
8.8
通讯作者：
Pearl LH
中科院分区：
文献类型：
--
作者：
Li Z;Zhou L;Prodromou C;Savic V;Pearl LH
抑制HSP90伴侣蛋白的atp酶循环可促进其客户蛋白的泛素化和蛋白酶体降解，其中包括许多致癌蛋白激酶。这为HSP90抑制剂作为癌症治疗药物提供了理论依据。然而，HSP90 atp酶抑制触发泛素化的机制尚不清楚，所涉及的E3泛素连接酶在很大程度上是未知的。使用siRNA筛选，我们已经确定了HSP90客户激酶CRAF的两个独立降解途径的组成部分。前者需要CUL5、伸长蛋白B和伸长蛋白C，后者需要E3连接酶hector 3，该酶也参与了MASTL和LKB1的降解。hector 3通过其n端DOC结构域与细胞中的HSP90和CRAF相关，该结构域在肿瘤细胞中被突变破坏，激活MAP激酶信号。我们的数据表明，hector 3是一种肿瘤抑制因子，可调节这一重要的致癌信号通路的活性。siRNA筛选确定了调节HSP90导向的客户端降解的因素。在HSP90 atp酶抑制后，hector 3促进了CRAF降解。hector 3通过其DOC结构域与HSP90- cdc37 -CRAF相互作用。cra3依赖的肿瘤细胞下调了hector 3 E3连接酶活性。Li等人开发了一种HSP90抑制剂引发的蛋白激酶客户端降解的细胞试验，并筛选了介导这一过程的泛素/蛋白酶体系统成分。他们确定了hector 3是一种E3连接酶，指导CRAF降解，并通过其DOC结构域证明了它与HSP90/激酶复合物的相互作用。
Inhibition of the ATPase cycle of the HSP90 chaperone promotes ubiquitylation and proteasomal degradation of its client proteins, which include many oncogenic protein kinases. This provides the rationale for HSP90 inhibitors as cancer therapeutics. However, the mechanism by which HSP90 ATPase inhibition triggers ubiquitylation is not understood, and the E3 ubiquitin ligases involved are largely unknown. Using a siRNA screen, we have identified components of two independent degradation pathways for the HSP90 client kinase CRAF. The first requires CUL5, Elongin B, and Elongin C, while the second requires the E3 ligase HECTD3, which is also involved in the degradation of MASTL and LKB1. HECTD3 associates with HSP90 and CRAF in cells via its N-terminal DOC domain, which is mutationally disrupted in tumor cells with activated MAP kinase signaling. Our data implicate HECTD3 as a tumor suppressor modulating the activity of this important oncogenic signaling pathway. siRNA screen identifies factors regulating HSP90-directed client degradation HECTD3 promotes CRAF degradation after HSP90 ATPase inhibition HECTD3 interacts with HSP90-CDC37-CRAF via its DOC domain CRAF-dependent tumor cells downregulate HECTD3 E3 ligase activity Li et al. develop a cellular assay for HSP90-inhibitor-triggered degradation of protein kinase clients and screen for components of the ubiquitin/proteasome system that mediate this. They identify HECTD3 as an E3 ligase that directs CRAF degradation and demonstrate its interaction with HSP90/kinase complexes via its DOC domain.